Telephone system.



F. M. SLOUGH.

TELEPHONE SYSTEM.

APPLICATION I'ILED AUG.I4. I914.

1,238,350. Patented Aug. 28, 1917.

IN VEN'T OR.

w QLFW UNITED STATES PATENT OFFIOE.

FRANK M. SLOUGI-I, OF ELYRIA, OHIO, ASSIGNOR, BY MESNE ASSIGNMENTS, TO STROMBERG-GARLSON TELEPHONE MFG. 00., OF ROCHESTER, N. Y., A CORPORA- TION OF NEW YORK.

TELEPHONE SYSTEM.

Specification of Letters Patent;

Patented Aug. 28, 1917.

. To all whom it may concern:

Be it known that I, FRANK M. SLoUoI-I, a citizen of the United States, residing at Elyria, Lorain county, Ohio, have invented certain new and useful Improvements in Telephone Systems; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

My invention relates to telephone systems, and more particularly I aim to produce a system in which the subscribers are guaranteed a secret conversation, the object of my invention being to automatically out the operator on when the central station circuit is connected with the calling line, and automatically cut her off when connection is made with the called line. I aim to accomplish this object in a simple and efficient manner, reducing the number of relays which have to be employed, and thereby enabling my invention to be installed in switchboard cabinets constructed for circuits now in use, without increasing the capacity of the cabinets to take care of several additional relays.

Other objects of my invention and the invention itself will be better understood from a description of one or two embodiments of the invention.

Figure 1 is an embodiment of my invention employed with a three-conductor link circuit.

Fig. 2 is an embodiment employed with a two-conductor link circuit.

Referring first to the embodiment shown in F 1, at I and II are shown telephone lines which lead from substations A and B to a central station O. For the sake of convenience, we will assume that I is the calling line and II the called line. I have shown single party lines, though mult-i-party lines may be used as well. Suitable means are provided at the main station O for connecting telephone lines together. I here show link conductors in the shape of a cord circuit D. Suitable switching means are provided for connecting the cord to the line, here shown as jacks J, J and plugs'P, P. The cord circuit in Fig. 1 consists of the link conductors l, 2 and 3, l and 2 constituting the talking strand and 3, the third strand of the cord circuit. The substation set consists of the usual apparatus, here shown as transmitter E, receiver F, bell H, condenser L and hook switch K, at the station A; transmitter E, receiver F, bell H, condenser L and hook switch K at station B. The line relays are shown at M, M; the line lamps at N, N and the cut-off relays at O, O. The operators set at the main station is shown at Q, and here consists of the usual apparatus, including transmitter R and receiver S. The supervisory lamps are shown at T, T; the supervisory relays at U, U and V, V. At X is shown a relay controlling the connection and disconnection of the operators set to the talking strands of the cord circuit. This relay is provided with two coils Y and Z and an armature WV. The armature W is pivoted at 6 and the coil Z is stronger than the coil Y as indicated by the fact that there are more windings upon this coil.

The apparatus shown in Fig. 1 operates as follows, assuming that the subscriber A desires to communicate with the subscriber B: Upon the closing of the switch K, a circuit will be completed through the relay M and the battery 5, which will complete a circuit through the line lamp N, signaling the operator for a connection. The operator inserts the plug'P into the jack J, completing a circuit through the cut-off relay O, the supervisory relay V, and the battery I), and energizing these relays. The relay O cuts oil? the line signal N and the line relay M. The relay V will be energized, but the supervisory lamp T will not be operated because at the time the circuit through the relay V was completed, a circuit through the relay U was completed over the talking strands of the cord, and the limbs of the line I. This relay w ll interrupt the circuit of the lamp T at 9-10. When the plug P is inserted into the jack J, a circuit will also be completed for the winding Y of the relay X, as follows: ground gbattery Zconductor 1l--winding Y conductor 12conductor 13contact D of the plug P-thimble 15 of the jackconductor 16-O-17to ground at 18. The winding Y will be energized, attracting the end 19 of the armature W and moving the same about the pivot 6, so that the contact 20 engages with the contact 21 and the contact 22 engages with the contact 23, connecting the operators set Q to the talking strands of the cord circuit through the lines 241, 25. The operator will then communicate with the subscriber at A over the following circuit beginning at the receiver S of the set Q,conductor 2420- 19-"2Tcondenser ZS-conductor 1-tip 29 of the plugtip spring 30limb 31 of the calling lineK-7E-F32sleeve spring33sleeve contact of the plug 34- conductor 2condenser 35conductor 36 23-S2225condenser 10-coil 41, back to Learning that it is the subscriber .at B that is wanted, the operator will, assuming that the line 11 is idle, insert the plug P into the jack J. This will complete a circuit through the winding Z of the relay X,as follows gb 11 Z 505152O to ground at 53, energizing the coil Z, which being stronger than the coil Y, will overcome the effects of the coil Y and return the armature 'W to its'normal position shown in Fig. 1, disconnecting the operator from the talking strands of the cord-circuit. It will thus be seen that the operator is permanentlyand effectively disconnected from the cord circuit, and that she cannot listen in upon the conversation which follows the ringing and answering of the called subscriber.

hen the conversation is finished, the supervisory signal is operated in .the well known way, and the system is restored to normal.

In the operation of the form shown in Fig. 2, the circuit of the winding Y will be completed when the plug P, is insertedinto the jack J as follows: ground g battery b conductor 111winding Y conductor 112portion 113 of the talking strand 11% of the cord circuit contact 115 of the plug-contact 116 of the jack-conductor 117 relay 118-to ground at v119. The winding Y will be energized, attracting the armature V to overcome the action of the spring 120, closing the switches 121* 19.2 and 123-124: and completing the connection of the operators set (I), tothe cord circuit through the conductors 130 and 131.

hen the plug P, is inserted into the jack J, a circuit is completed forthe winding Z of the relay X,, as follows: g -bat 'terv Z) 111Z,-1401 11portion 142 of the talking strand14e314-1145146 to ground at 14.7. The winding Z being stronger than .the winding Y attracts the armature 1V rotating it about the pivot 150 .and disconnecting the operators set from the cord circuit.

The other features of the operation of this circuit will be apparent from the description of the operation of the circuit in Fig. 1.

It will be apparent that the coils Y and Z of the relay X may be inountedinany suitable manner, and thattheymay be so placed together as to make a very compact struc necting the lines together, switching means for connecting the link conductors to the telephone lines, an operators set, conductors for connecting the'operator's setto the link conductors, :apparatus controlling such operators set conductors, said apparatus including a ditlerentialrelay, one of the windings of which 18 stronger than the other windin a circuit for .each winding, in eluding aportion of the talking strand and contacts of said switching means.

2. In a telephone system, the combination of telephone lines, a cord circuit ator connecting the linestogether, plug .and ack switching means for connecting thelink conductors to the telephone lines,.an operators set, conductors .forconnecting theoperators set to the-cord circuit, apparatus including a differential relay, controlling said conductors, one of the windings of said relay .being stronger than theother, a circuit for each relay winding, includinga portion of the talking strand and plug and jack contacts.

3. In a telephone system,.theconibination of a called and a calling l1ne,.a cord circuit,

an answering switclrtoconnect the cord to the calling llne, a calling switch to connect the cord to the called line, an operatofls set and means including a differential relay to connect and disconnect said set to said cord, said relay having two windings, one stronger than the other, and a circuit for .the stronger winding including a portion of a talking strandof the cord .and contacts of.the calling switch.

In witness whereof, .I have signed my name in the presence of two witnesses this 3rd day of August, 1914-.

FRANK 'M. SLOUGH.

Witnesses:

GEO. E. ROBERTS, J. C. SNYDER.

.flopies of this patent may be obtained for five cents each. by addressing the .Gommissioner of Patents,

Washington, D. .9. 

